Abstract Standardization of orders using computerized provider order entry (CPOE) systems has been shown to improve care quality and safety, resulting in reduced overall costs. Nevertheless, recent reports have identified risks and unintended consequences of CPOE-based medication ordering including medication ordering errors and adverse drug events. While there has been significant research on CPOE-based medication errors, these studies have either been localized (e.g., using retrospective methods) or relied on identifying specific errors (e.g., using systemic alerts). While these methods are useful, a more comprehensive and holistic mechanism for studying CPOE-based medication ordering errors is needed. In this proposal, we evaluate a CPOE-based function?medication voiding?that can be used to prospectively identify and document medication errors. Medication voiding supports the identification of an existing medication order as an error, and then removing it from a patient's existing medication list (i.e., by ?voiding? the order). Guided by principles and methods from human factors and medical error research, we investigate: (a) the characteristics of medication voiding, and (b) the clinician perceived reasons for medication voiding. In response to the AHRQ SEN on Health IT (NOT-HS-16-009), our exploratory study on medication voiding will be instrumental in establishing the viability of a HIT-integrated function for tracking and evaluating medication ordering errors. Study findings can help us to: (1) determine the appropriateness of using medication voiding as a mechanism for tracking, documenting, studying medication ordering errors and their interception; (2) identify investigate clinician provided reasons for CPOE-based medication voiding; and (3) investigate clinician- provided insights on the use of the voiding function that will be instrumental in developing user- centered insights for improving the usability, and streamlining it within clinician medication ordering workflow.